1. Field of the Invention
The present invention relates to a back-up plate up/down apparatus, more particularly, to a back-up plate up/down apparatus in which a back-up plate is ascended or descended without rocking, maintaining a parallel state.
2. Description of the Background Art
A large number of electronic components are mounted on a surface of a printed circuit board in order to be connected with each other electrically. The mounting of the electronic components is performed by a surface mounting apparatus, and the mounting of the electronic components comprises the steps of: supplying a printed circuit board(hereinafter, referred to a xe2x80x9cboardxe2x80x9d); transferring the supplied board; mounting the electronic components on the board; and carrying out the board mounted the electronic components.
As shown in FIG. 1, the mounting apparatus of electronic components according to the conventional art comprises: a plurality of conveyors C1, C2 and C3 arranged in a line for transferring the board P; an electronic components supplying unit 1 installed to at least one side of the conveyor C2 being mounted the electronic components among the plurality of conveyors C1, C2 and C3 and loaded the electronic components; a mounting head 3 for mounting the electronic components 2 to the board P by picking the electronic components 2 from the electronic components supplying unit 1.
The conveyors C1, C2 and C3 have belts B1, B2 and B3 being mounted on a side thereof at regular intervals.
A first conveyor C1 among the conveyors C1, C2 and C3 is a carry-in buffer conveyor being for carrying-in the board, a third conveyor C3 is a carry-out buffer conveyor for carrying-out the board mounted the electronic components, and a second mounting conveyor C2 between the first and third buffer conveyors is for mounting the electronic components. The respective conveyors C1, C2 and C3 are installed to a frame 4a and also driven independently by a driving means, respectively.
The mounting head 3 is moved at X and Y shafts by gantries of X and Y shafts and sucks the electronic components in the electronic components providing unit 1 by vacuum, thereby mounting the electronic components to the board.
On the other hand, only the both sides of the board P is supported by belts, so that there may be occurred a bending transformation being bent its central portion downwardly. That is, the central portion of the board P is bent downwardly by a load applied when mounting the electronic components and so the electronic components may be escaped from its mounting position.
In order to prevent from occurring the above wrong phenomenon, an apparatus comprises a supporting means for supporting the board P transferred from a lower portion of a mounting area of the electronic components to the mounting area.
The board supporting means comprises: a back-up plate 4; a plurality of back-up pins 5 installed on a top surface of the back-up plate 4 and contacted with a bottom surface of the board P for supporting the board P; and an up/down means(not shown) installed to a lower side of the back-up plate 4 for moving the back-up plate 4 upwardly/downwardly.
As shown in FIG. 2, the up/down means comprises: an up/down guide 6 installed to the lower side of the back-up plate 4 and having an inclination surface 6a inclined upwardly toward one direction; and an up/down roller 7 capable of rolling along the inclination surface 6a of the up/down guide 6. That is, when the up/down roller 7 rolls along the inclination surface 6a, the height of the up/down roller 7 changes according to the change of height of the inclination surface and so the back-up plate 4 is moved upwardly and downwardly.
As constructed above, an operation of the electronic components mounting apparatus according to the conventional art will be described as follows.
The board carried by the first conveyor C1 is transferred to the second conveyor C2 as the mounting area, when the board is transferred to the second conveyor C2, the transfer of the board P is stopped temporarily by a stopper(not shown) and then a board support means of a lower side of the board is operated.
The up/down roller 7 rolls and ascends along the inclination surface 6a of the up/down guide 6 and so the back-up plate 4 is moved upwardly and the back-up pin 5 supports the board at a lower side.
In the state that the board is supported, the mounting head 3 is moved toward X and Y shaft directions and so the electronic components are mounted to the board by the mounting head 3.
When completing the mounting work, the stopper blocking the progress of the board is descended and simultaneously, the up/down roller 7 is moved downwardly along the inclination surface 6a, so that the back-up pin 5 is detached from the bottom surface of the board P.
The board mounted the electronic components by the third conveyor C is carried out and a new board is transferred to the second conveyor.
However, in the back-up plate up/down apparatus of the electronic components mounting apparatus according to a conventional art, several problems exist as follows.
The up/down roller 7 for moving the back-up plate 4 upwardly and downwardly is worn away partly according to the passing of a year and also when processing the inclination surface 6a, because its surface may be uneven, the back-up plate 4 does not smoothly move upwardly and downwardly and is rocked. Also, the degree of the up/down of the back-up plate 4 according to the inclination surface 6a of the up/down guide 6 is determined and the processing of the inclination surface 6a is difficult.
Accordingly, it is a primary object of the present invention to provide a back-up plate up/down apparatus in which the back-up plate supporting a board at a lower side is smoothly moved upwardly and downwardly.
Another object of the present invention is to provide a back-up plate up/down apparatus in which the board can be supported without settling a board minutely and rocking components.
In one aspect of the present invention, to achieve the above-described objects of the invention, there is provided a back-up plate up/down apparatus including: a base plate; a plurality of guide blocks installed with a constant distance to the base plate; one or more first driving means installed between the guide blocks; fixed blocks installed with a constant distance to both ends of the base plate and having rotating shafts inserted to both ends thereof; a plurality of rotating links, the respective rotating link in which the rotating shaft is inserted to an end thereof and a connecting member is connected to the other end thereof; a second driving means connected to the connecting members by means of a rod; at least one or more holders fixed at rods of other connecting members slidably and for fixing the back-up plate; and a plurality of sensors installed to the holders with a constant distance.
Preferably, the first and second driving means are pneumatic cylinders.
More preferably, the first driving means is a motor.
More preferably, a key may be installed to a connecting portion of the rotation link and the rotating shaft in order to prevent from clamping and distorting the rotation shaft.
More preferably, the guide block is installed to a lower side of the holder and guides the vertical direction movement of the back-up plate.
More preferably, an elastic means and a buffer means may be installed between the guide block and the holder.